US7652820B2 - Reflective LCD projection system using wide-angle cartesian polarizing beam splitter and color separation and recombination prisms - Google Patents

Reflective LCD projection system using wide-angle cartesian polarizing beam splitter and color separation and recombination prisms Download PDF

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US7652820B2
US7652820B2 US11315721 US31572105A US7652820B2 US 7652820 B2 US7652820 B2 US 7652820B2 US 11315721 US11315721 US 11315721 US 31572105 A US31572105 A US 31572105A US 7652820 B2 US7652820 B2 US 7652820B2
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color
pbs
light
prism
system
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US20060098284A1 (en )
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David J. W. Aastuen
Charles L. Bruzzone
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3M Innovative Properties Co
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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00Details of colour television systems
    • H04N9/12Picture reproducers
    • H04N9/31Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3102Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM] using two-dimensional electronic spatial light modulators
    • H04N9/3105Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM] using two-dimensional electronic spatial light modulators for displaying all colours simultaneously, e.g. by using two or more electronic spatial light modulators
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B27/00Other optical systems; Other optical apparatus
    • G02B27/10Beam splitting or combining systems
    • G02B27/1006Beam splitting or combining systems for splitting or combining different wavelengths
    • G02B27/102Beam splitting or combining systems for splitting or combining different wavelengths for generating a colour image from monochromatic image signal sources
    • G02B27/1026Beam splitting or combining systems for splitting or combining different wavelengths for generating a colour image from monochromatic image signal sources for use with reflective spatial light modulators
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B27/00Other optical systems; Other optical apparatus
    • G02B27/10Beam splitting or combining systems
    • G02B27/14Beam splitting or combining systems operating by reflection only
    • G02B27/145Beam splitting or combining systems operating by reflection only having sequential partially reflecting surfaces
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B27/00Other optical systems; Other optical apparatus
    • G02B27/28Other optical systems; Other optical apparatus for polarising
    • G02B27/283Other optical systems; Other optical apparatus for polarising used for beam splitting or combining
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B5/00Optical elements other than lenses
    • G02B5/30Polarising elements
    • G02B5/3025Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
    • G02B5/3033Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
    • G02B5/3041Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks
    • G02B5/305Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks including organic materials, e.g. polymeric layers
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B5/00Optical elements other than lenses
    • G02B5/30Polarising elements
    • G02B5/3025Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
    • G02B5/3058Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state comprising electrically conductive elements, e.g. wire grids, conductive particles
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00Details of colour television systems
    • H04N9/12Picture reproducers
    • H04N9/31Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3141Constructional details thereof
    • H04N9/315Modulator illumination systems
    • H04N9/3167Modulator illumination systems for polarizing the light beam

Abstract

An optical imaging system including an illumination system, a Cartesian PBS, and a prism assembly. The illumination system provides a beam of light, the illumination system having an ƒ/# less than or equal to 2.5. The Cartesian polarizing beam splitter has a first tilt axis, oriented to receive the beam of light. A first polarized beam of light having one polarization direction is folded by the Cartesian polarizing beam splitter and a second polarized beam of light having a second polarization direction is transmitted by the Cartesian polarizing beam splitter. The Cartesian polarizing beam splitter nominally polarizes the beam of light with respect to the Cartesian beam splitter to yield the first polarized beam in the first polarization direction. The color separation and recombination prism is optically aligned to receive the first polarized beam. The prism has a second tilt axis, a plurality of color separating surfaces, and a plurality of exit surfaces. The second tilt axis may be oriented perpendicularly to the first tilt axis of the Cartesian polarizing beam splitter so that the polarized beam is nominally polarization rotated into the second polarization direction with respect to the color separating surfaces and a respective beam of colored light exits through each of the exit surfaces. Each imager is placed at one of the exit surface of the color separating and recombining prism to receive one of the respective beams of colored light, wherein each imager can separately modulate the polarization state of the beam of colored light.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No. 09/746,933 filed Dec. 22, 2000, now issued as U.S. Pat. No. 7,023,602, which claims benefit of U.S. Provisional Application No. 60/178,973, filed Jan. 25, 2000, both of which are incorporated by reference. Prior cases U.S. patent application Ser. No. 09/312,917, filed on May 17, 1999, issued as U.S. Pat. No. 6,486,997, U.S. patent application Ser. No. 08/958,329 filed Oct. 28, 1997, issued as U.S. Pat. No. 5,965,247 and Ser. No. 09/126,917, filed Jul. 31, 1998, abandoned, are also incorporated by reference.

BACKGROUND OF THE INVENTION

This invention relates to the use of 3M Cartesian polarizing beam splitter (“PBS”) films to make electronic projection systems that use color separation and recombination prisms (e.g. Philips Prisms) with very efficient, low ƒ/# optical beams while preserving high contrast. More specifically, the present invention relates to an optical imaging system including a reflective imager and a Cartesian wide-angle PBS having a fixed polarization axis and using the tilted reflective surfaces of a Philips prism.

Optical imaging systems may include a transmissive or a reflective imager or light valve. Traditional transmissive light valves allow certain portions of a light beam to pass through the light valve to form an image. By their very function, transmissive light valves are translucent; they allow light to pass through them only where required electrical conductors and circuits are not present. Reflective Liquid Crystal on Silicon (“LCOS”) imagers, in turn, reflect selected portions of the input beam to form an image. Reflective light valves provide important advantages, as controlling circuitry may be placed below the reflective surface, so that these circuits do not block portions of the light beam as in the transmissive case. In addition, more advanced integrated circuit technology becomes available when the substrate materials are not limited by their opaqueness. New potentially inexpensive and compact liquid crystal display (“LCD”) projector configurations may become possible by the use of reflective LC microdisplays. Reflective LCOS imagers in the past have been incorporated into inefficient, bulky and expensive optical systems.

For projection systems based on reflective LCD imagers, a folded light path wherein the illuminating beam and projected image share the same physical space between a PBS and the imager offers a desirably compact arrangement. A PBS is an optical component that splits incident light rays into a first polarization component and a second polarization component. Traditional PBS's selectively reflect or transmit light depending on whether the light is polarized parallel, or perpendicular to the plane of incidence of the light: that is, a plane defined by the incident light ray and a normal to the polarizing surface. The plane of incidence also is referred to as the reflection plane, defined by the reflected light ray and a normal to the reflecting surface.

Based on the operation of traditional polarizers, light has been described as having two polarization components, a p-component or direction and a s-component or direction. The p-component corresponds to light polarized parallel to the plane of incidence. The s-component corresponds to light polarized perpendicular to the plane of incidence. A so-called MacNeille PBS will substantially reflect s-polarized light incident on the PBS surface (placed along the diagonal plane connecting two opposing edges of a rectangular glass prism), and substantially transmit p-polarized light incident upon this surface. Traditional MacNeille PBS technology is known and is described in U.S. Pat. No. 2,403,731 and in H. A. Macleod, Thin Film Optical Filters, 2nd Edition, McGraw-Hill Publishing Co., 1989, pp. 328-332.

To achieve the maximum possible efficiency in an optical imaging system, a low ƒ/# system is desirable (see, F. E. Doany et al., Projection display throughput; Efficiency of optical transmission and light-source collection, IBM J. Res. Develop. V42, May/July 1998, pp. 387-398). The ƒ/# measures the light gathering ability of an optical lens and is defined as:
ƒ/#=f(focal length)÷D(diameter or clear aperture of the lens)

The ƒ/# (or F) measures the size of the cone of light that may be used to illuminate an optical element. The lower the ƒ/#, the faster the lens and the larger the cone of light that may be used with that optical element. A larger cone of light generally translates to higher light throughput. Accordingly, a faster (lower ƒ/#) illumination system requires a PBS able to accept light rays having a wider range of incident angles.

The maximum incident angle θmax (the outer rays of the cone of light) may be mathematically derived from the ƒ/#, F:
θmax=tan−1((2F)−1)

Traditional folded light path optical imaging systems have employed the previously described optical element known as a MacNeille PBS. MacNeille PBSs take advantage of the fact that an angle exists, called Brewster's angle, at which no p-polarized light is reflected from an interface between two media of differing index. Brewster's angle is given by:
θB=tan−1(n 1 /n 0),

where n0 is the index of one medium, and n1 is the index of the other. When the angle of incidence of an incident light ray reaches the Brewster angle, the reflected beam portion is polarized in the plane perpendicular to the plane of incidence. The transmitted beam portion becomes preferentially (but not completely) polarized in the plane parallel to the plane of incidence. In order to achieve efficient reflection of s-polarized light, a MacNellie PBS is constructed from multiple layers of thin films of materials meeting the Brewster angle condition for the desired angle. The film thicknesses are chosen such that the film layer pairs form a quarter wave stack.

There is an advantage to this construction in that the Brewster angle condition is not dependent on wavelength (except for dispersion in the materials). However, MacNeille PBSs have difficulty achieving wide-angle performance due to the fact that the Brewster angle condition for a pair of materials is strictly met at only one angle of incidence. As the angle of incidence deviates from this angle, a spectrally non-uniform leak develops. This leak becomes especially severe as the angle of incidence on the film stack becomes more normal than the Brewster's angle. As will be explained below, there are also contrast disadvantages for a folded light pat projector associated with the use of p- and s-polarization, referenced to the plane of reflection for each my.

Typically, MacNellie PBSs are contained in glass cubes, wherein a PBS thin-film stack is applied along a diagonal plane of the cube. By suitably selecting the index of the glass in the cube, the PBS may be constructed so that light incident normal to the face of the cube is incident at the Brewster angle of the PBS.

MacNeille-type PBSs reportedly have been developed capable of discrimination between s- and p-polarized light at f/#'s as low as f/2.5, while providing extinction levels in excess of 100:1 between incident beams of pure s- or pure p-polarization. Unfortunately, as explained below, when MacNeille-type PBS's are used in a folded light pat with reflective imagers, the contrast is degraded due to depolarization of rays of light having a reflection plane rotated relative to die reflection plane of the central ray. As used below, the term “depolarization” is meant to describe the deviation of the polarization state of a light ray from that of the central light ray. As light in a projection system generally is projected as a cone, most of the rays of light are not perfectly parallel to the central light ray. The depolarization increases as the f/# decreases, and is magnified in subsequent reflections from color selective films. This “depolarization cascade” has been calculated by some optical imaging system designers to effectively limit the f/# of MacNellie PBS based projectors to about 3.3, thereby limiting the light throughput efficiency of these systems. See, A. E. Rosenbluth et al., Contrast properties of reflective liquid crystal light valves in projection displays, IBM I. Res. Develop. V42, May/July 1998, pp. 359-386, (hereinafter “Rosenbluth Contrast Properties”) relevant portions of which are hereby incorporated by reference.

Recently, Minnesota Mining and Manufacturing has developed a novel type of birefringent polymeric multi-layer polarizing film (“3M Advanced Polarizing Film” or “APF”). Co-assigned and (co-pending) parent application U.S. Ser. No. 09/312,917, issued as U.S. Pat. No. 6,486,997, mentions the use of such a film as a PBS. European Patent Application EP 0 837 351 A2 attempts to utilize another 3M Dual Brightness Enhancing Film (“DBEF”), an early 3M multi-layer film material, in a projection display apparatus having a “wide-angle” reflecting polarizer. Such reference refers to p- and s-differentiation and uses the 3M material as a common reflective polarizer. Moreover, while “wide-angle” performance is a widely recognized design goal, references to “wide-angle” are meaningless absent contrast limits and spectral leak reduction and teachings on how to achieve such a goal. The 3M product DBEF is a reflective polarizer with typical block direction leakages of 4 to 6 percent at normal incidence. At higher angles the leakage is somewhat reduced, but at 45 degrees the extinction is typically still a few percent. Contrast ratios when using DBEF typically will be limited to maximum values at or below 99:1 for white light. However, DBEF suffers from spectral leaks that reduce the contrast of certain color bands to as low as 25:1, depending on the nature of the illumination source and the exact DBEF sample. To obtain superior performance it is desirable that good screen uniformity and the absence of spectral leaks in the dark state accompany good average contrast in all relevant color bands.

There has been previous work with non-telecentric configuration, reported by Paul M. Alt in the Conference Record of the 1997 International Display Research Conference (p. M 19-28) and in the IBM Journal of Research and Development (Vol. 42, pp. 315-320, 1998). These systems, however, used conventional MacNeille PBS cubes rather than a Cartesian PBS, and achieved a contrast ratio of only 40:1 at ƒ/5. The PBS and the color prism were used in an s-orientation.

The need remains for an optical imaging system that includes truly wide angle, fast optical components and that may allow viewing or display of high-contrast images. Furthermore, it is desirable to enable optical designs that minimize the size of individual components, such as the color separation prism.

A color separation prism receives the polarized beam of light and splits the beam, generally into three-color components. Color prisms and imagers naturally have an orientation, including a long axis and a short axis. Optical designers are presently constrained to one of two options. The first is to place the imager on the color prism such that the long axis of the imager is parallel to the long axis of the color prism exit aperture (to the imagers). This allows the use of smallest possible color prism, but under this condition, if the tilt axes of the PBS and the color prism are kept parallel to each other, then the designer is constrained to build the projector in a tower configuration. Such a configuration places the longest dimension of the projector in a vertical orientation, which may be unsuitable for a variety of applications. The second option is to place the long axis of the imager along the short direction of the color prism exit aperture (to the imagers). This allows the use of more desirable low-profile projector configurations, wherein the longest dimension of the projector is horizontal. However, this requires that the color prism be made larger and therefore that the projection lens have a longer back focal length. Consequently, this configuration will require larger, heavier, and more expensive projection lens and color prism components.

SUMMARY OF THE INVENTION

The present invention describes an optical imaging system including and advantageously employing a wide-angle “Cartesian” polarizer beam splitter (“PBS”) and a Philips prism for separating and recombining separate color bands. The optical imaging system of the present invention is capable for use with “fast” (low ƒ/#) optical beams while providing a high contrast ratio. The term optical imaging system is meant to include front and rear projection systems, projection displays, head-mounted displays, virtual viewers, heads-up displays, optical computing, optical correlation and other similar optical viewing and display systems. A Cartesian PBS is defined as a PBS in which the polarization of separate beams is referenced to invariant, generally orthogonal principal axes of the PBS. In contrast with a MacNeille PBS, in a Cartesian PBS the polarization of the separate beams is substantially independent of the angle of incidence of the beams. The use of a Cartesian PBS film also allows the development of systems using curved PBS that provide higher light output and/or replace or augment other optical components.

A wide-angle PBS is defined as a PBS capable of receiving a cone of light rays with an angle of incidence up to 11° (in air) or more, while maintaining acceptable system contrast. By recognizing and advantageously applying properties of wide-angle Cartesian polarizers, the present invention discloses a high-efficiency optical imaging system capable of functioning at ƒ/#'s equal to or below ƒ/2.5 while maintaining a contrast ratio of at least 100 to 1, or, more preferably, 150 to 1 in a projection system configuration.

An embodiment of an optical imaging system in accordance with the present invention includes a wide-angle Cartesian PBS, light valve illumination optics having an ƒ/#≦2.5, a color separation and recombination prism and at least two reflective light valves. The Cartesian PBS has a structural orientation defining fixed polarization axes. A reflective Cartesian PBS substantially reflects those components of a beam of light that are polarized along one such fixed axis, called the Material Axis. Those components of a beam of light with polarization not along the Material Axis are substantially transmitted. The PBS therefore splits incident light into a first and a second substantially polarized beam having polarization states referenced to the fixed polarization axes and the PBS directs the first polarized beam onto the reflective light valve. In an exemplary embodiment, the Cartesian PBS includes 3M's APF. In other exemplary embodiments, the PBS may include a wire grid polarizer, such as those described in Schnabel et al., “Study on Polarizing Visible Light by Subwavelength-Period Metal-Stripe Gratings”, Optical Engineering 38(2), pp. 220-226, February 1999, relevant portions of which are hereby included by reference. Other suitable Cartesian polarizers also may be employed.

The light valve illumination optics have an ƒ/# of at most 2.5, a minimum cone angle of about 11 degrees (in air) and the system has a contrast ratio exceeding 100 to 1 using an ideal imager. In preferred embodiments, the contrast ratio exceeds 150 to 1 and the illumination optics have an ƒ/# equal or less than 2.2. The illumination optics are those optics that condition (e.g., pre-polarize, shape, homogenize and filter) the light beam. The ƒ/# is associated with the beam of light incident on the imager.

The light valves or imagers may be a polarization modulating light valve, including smectic or nematic liquid crystal light valves. The optical imaging system may further comprise a pre-polarizer that polarizes input light into pre-polarized light, the pre-polarized light comprising the incident light on the PBS. The optical imaging system also includes a color separation and recombination prism assembly or mirrors and a plurality of reflective light valves (i.e., imagers). The prism assembly has a second tilt axis, a plurality of color separating surfaces, and a plurality of exit surfaces. The prism receives the polarized light from the PBS, separates the polarized light into a plurality of colors and directs polarized color beams to each light valve. The optical imaging system may include a suitable light source that supplies the incident light.

In alternative embodiments, the reflective light valve may reflect at least a portion of the first polarized beam back to the original PBS or to a second PBS.

As stated above, a color prism exit aperture (to the imagers) has an orientation, including a long axis and a short axis. If an optical designer places the imager on the color prism such that the long axis of the imager is parallel to the long axis of the color prism exit aperture, then the designer will achieve the smallest and lightest projector configuration. However, under this condition, because traditionally the tilt axes of the PBS and the color prism are constrained to be parallel to each other, then the designer is constrained to build a tower configuration. Alternatively, a larger color prism can be made to accommodate the imager oriented perpendicularly to the configuration discussed above, but such an orientation has the disadvantages of increasing the size, weight, and cost of the color prism. It also results in a longer back focal length for the projection lens, adding to the complexity, size and expense of this lens. The use of a Cartesian PBS was found to enable the rotation of the color prism such that the tilt axis for the color separating coatings are orthogonal to the tilt axis of the PBS. This allows the user the option to build either a tower of a flat configuration without weight, size, or cost penalty.

It is highly desirable that the prism be capable of orientation with the tilt axes of its color separation surfaces either parallel to that of the PBS's polarization separation surface or perpendicular to it, as the designer desires. This allows the system designer to have maximum flexibility with regard to industrial design, cooling, imager placement and other practical projection system considerations. The combination of the Cartesian PBS and the color prisms can, at low ƒ/#, enable the color prism and PBS to have crossed tilt axes and obtain good contrast. This allows a flat, low profile orientation with minimized CP size, which is particularly desirable for portable front projection systems. The present work details specific types of color prism to be used, as well as prism orientation to achieve desirable results.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 a and 1 b are schematic plan views of two embodiments of projection systems in accordance with the present invention.

FIGS. 2 a and 2 b are side perspective views of a first and a second PBS and color prism assembly oriented with parallel and perpendicular tilt axes in accordance with the present invention.

FIG. 3 is a graph of APF Cartesian PBS dynamic range of contrast performance vs. wavelength of light.

FIG. 4 is a graph of APF Cartesian PBS of contrast performance vs. ƒ/#.

FIGS. 5 a and 5 b are graphs of the contrast and dark and bright state spectral radiance vs. wavelength for PBS and color prism with parallel tilt axes.

FIG. 6 is a pupil image of dark state Maltese band for a parallel, s-oriented PBS and color prism.

FIG. 7 is a pupil image of a dark state Maltese band for APF PBS without color prism.

FIG. 8 a is a graph of contrast vs. wavelength for PBS and color prism with crossed tilt axes.

FIG. 8 b is a graph of dark and bright state spectral radiance for PBS and color prism with crossed tilt axes.

FIG. 9 is a dark state pupil image of Maltese band for perpendicular tilt axes.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 a and 1 b are schematic plan views of projection systems in accordance with the present invention. FIG. 1 a illustrates an f/2 test system according to the present invention having a PBS and color prism assembly oriented with parallel tilt axes. FIG. 1 b illustrates an f/2 test system according to the present invention having a PBS and color prism assembly oriented with perpendicular or orthogonal tilt axes. Referring to FIGS. 1 a, 1 b, 2 g and 2 b, the following reference numerals are used in the descriptions:

Part list:
12 Arc lamp
14 Elliptical reflector
16 Tunnel integrator
20 Telecentric illumination system
24 Telecentric stop
26a, 26b Telecentric lenses
28 Pre-polarizer
30 Polarization beam splitter (PBS)
32 Cartesian PBS film
36 Philips color prism assembly
38 Color prism exit aperture
38v “Vertical” dimension of CP
38h “Horizontal” dimension of CP
40b Blue imager
40g Green imager
40r Red imager
50 Projection lens
56 PBS tilt axis
58 CP tilt axes
60 Illumination optic axis
62 Optic axis through C

The tilt axes of the PBS and color separation prisms are shown as parallel in this embodiment. The long dimension of the color prism exit aperture is out of the page.

The present invention analyzes and recognizes a “depolarization cascade” problem that limits the ƒ/# of the illumination optics of traditional optical imaging systems using a PBS based on discrimination between p- and s-polarization states. Most reflective LCD imagers are polarization rotating; that is, polarized light is either transmitted with its polarization state substantially unmodified for the darkest state, or with a degree of polarization rotation imparted to provide a desired gray scale. A 90° rotation provides the brightest state in these PBS-based systems. Accordingly, a polarized beam of light generally is used as the input beam for reflective LCD imagers. Use of a PBS offers attractive design alternatives for both polarizing the input beam and folding the light path.

The exemplary system illustrated by FIGS. 1 a and 1 b differ in some ways from a commercial projector (e.g., there is no provision for converting nominally p-polarized light from the lamp into the desired s-polarization state to improve efficiency), but it does provide a flexible test system which allows easy modification of the ƒ/# of the illuminating beam of light. In the system of FIGS. 1 a and 1 b, light is emitted from a metal halide or high pressure mercury arc lamp, 12, and collected by elliptical reflector, 14. The converging beam of light from the lamp and reflector is inserted into a glass tunnel beam integrator, 16, which reflects the beam multiple times inside itself by total internal reflection. This results in a more uniform beam intensity being emitted at the down-stream end of the tunnel integrator than was inserted at the upstream end. The tunnel integrator should preferably have the same cross-sectional dimensions as the optically active pixel area of the imagers (40 b, 40 g, and 40 r) to be illuminated.

After being emitted from the tunnel integrator, the light is collected by the first telecentric lens 26 a of the telecentric illumination system, 20. This lens is located one focal distance from the emitting end of the tunnel integrator, 16, and transmits the light through the telecentric stop, 24, and onto the second telecentric lens, 26 b. Between the telecentric stop, 24, and the second telecentric lens, 26 b, we have placed a pre-polarizer 28 to polarize the light perpendicularly to the plane of FIGS. 1 a and 1 b. This is referred to as “vertically” or “nominally s-” polarized. The pre-polarizer, 28, could be placed at a number of places in the system, but the light intensity is lower near the telecentric stop, 24, than at other convenient places in the system. Placement of the pre-polarizer, 28, either directly before or after this stop therefore ensures maximum polarizer lifetime.

The resulting vertically polarized, telecentric beam then passes into the Cartesian PBS, 30, in which the Cartesian PBS film 32 is oriented to substantially reflect vertically polarized light. It is understood that the term “film” is not limiting, and could refer to, for example, the array of elements in a wire grid polarizer, or the 3M APF multilayer optical film polarizer. The light therefore passes into the Color Prism Assembly, 36, where it is separated into distinct red, green, and blue beams that illuminate the red, green and blue imagers (40 r, 40 g, and 40 b) respectively. For purposes of clarity, the Color Prism Assembly, 36, is shown in the conventional orientation with the tilt axes of the red and blue reflective coatings parallel to the tilt axis of the Cartesian PBS film, 32. While this orientation is necessary for the prior art, using MacNeill PBS's, it will be shown below that the employment of a Cartesian PBS film, 32, allows the rotation of the Color Prism Assembly, 36, by 90 degrees about the principle axis of the beam, so that the red and blue imagers in the figure would be oriented vertically with respect to one another in the figure, and the nominally s-polarized light from the PBS, 30, would be p-polarized with respect to the color selective surfaces of the Color Prism Assembly, 36.

This is further illustrated in FIGS. 2 a and 2 b. FIG. 2 a shows an arrangement in which the tilt axes, 58, of the Color Prism Assembly, 36, are parallel to the tilt axis, 56, of the PBS, 30. FIG. 2 b shows the arrangement made possible by a Cartesian PBS, 32, in which the tilt axes, 58, of the Color Prism Assembly, 36, are perpendicular to the tilt axis, 56, of the PBS, 30.

It should also be noted that the Color Prism Assembly employed in FIGS. 1 a and 1 b may be configured so that the green light beam is reflected along with either the red or blue beam, rather than having the green light pass undeflected onto the green imager. In that case, either the red or blue beam would pass undeflected onto its intended imager.

Each imager, 40 r, 40 g, and 40 b, is divided into many separate and independent picture elements (pixels), each of which can be individually addressed to rotate the polarization state of the incident light as it is reflected off each pixel. If a pixel element for a particular color channel is intended to be dark, then no polarization rotation occurs at that pixel on the appropriate imager, and the light is reflected back out through the Color Prism Assembly, 36, and into the PBS, 30. The light reaching the Cartesian PBS Film, 32, from this color pixel element is then still vertically polarized, and therefore reflected by the Cartesian PBS Film, 32, back through the telecentric system and into the lamp. Substantially, none of this light will propagate into the Projection Lens assembly, 50, and therefore substantially none will be projected onto the screen (not shown). If a pixel element for a particular color channel is intended to be bright, then polarization rotation occurs at that pixel on the appropriate imager, and the light is reflected back out through the Color Prism Assembly, 36, and into the PBS, 30. The light reaching the Cartesian PBS Film, 32, from this color pixel element is then at least partially horizontally polarized, and therefore partially substantially transmitted by the Cartesian PBS Film, 32, into the projection lens, and subsequently imaged onto the screen (not shown).

The degree of horizontal polarization imparted to the light reflected from each color pixel element will depend on the level of brightness desired from the particular color pixel at the time. The closer the rotation of the polarization approaches a pure horizontal polarization state at any given time, the higher the resulting screen brightness for that particular color pixel element at that particular time.

The present work details specific types of color prism, 36, to be used, as well as color prism, 36, orientation to achieve desirable results. It is highly desirable that the color prism, 36, be capable of orientation with its tilt axes either parallel to that of the PBS, 30, or perpendicular to it, as the designer desires. This allows the system designer to have maximum flexibility with regard to industrial design, cooling, imager placement and other practical projection system considerations. For example, the decision as to whether to make a tower configuration (where the shortest dimension of the projector is held horizontal in use) or a more conventional flat configuration (where the shortest dimension is held vertical in use) with the most compact possible color prism assembly would not be an option open to the designer in the absence of the aforementioned flexibility. The alternatives open to a designer using the configuration of FIGS. 1 a and 1 b have in the past been: a) design using the most compact possible color prism to accommodate the selected imager, but place the prism in a “tower” configuration, or b) design a larger color prism capable of accommodating the long, horizontal axis of the imager within the shorter dimension of the color prism face. In the second case the projector may be oriented in a flat configuration, but it will be larger and heavier than the alternate tower configuration. The former option may be undesirable for commercial and thermal reasons, while the latter is undesirable due to the premium placed on small size and weight in the marketplace. Because a Cartesian PBS prepares a sufficiently pure polarization state at usefully low ƒ/#, the color prism, 36, may be rotated 90° about the optic axis, 62, when the Cartesian PBS is employed. This enables the usage of a smaller color prism, 36, for the horizontal projector layout.

EXAMPLES

A 3M APF type Cartesian polarizer film was used as a polarization splitting surface, which allows the PBS film to be placed in a glass cube, similarly to a MacNeille PBS. An advantage of the APF type PBS is that, unlike the MacNeille PBS, it may be used with glass of any index. This allows flexibility for selecting glasses with different properties that may be desirable for different applications. Examples include low blue light absorption where color gamut and balance is important, or low stress optic coefficient for high light intensity applications, or higher index of refraction for smaller angular spread in the glass, allowing smaller components where compact design is important. Secondly, because tilted color separation coatings such as those used in color prisms are sensitive to angle, a fully telecentric beam was used for these experiments. This beam provides a full ƒ/2 cone at all points on the imager, thereby ensuring that all allowable rays of light in an ƒ/2 beam are represented at all image locations in our tests. The system has been designed for maximum flexibility, for example to allow easy changes of illumination ƒ/#.

The PBS 30 in FIGS. 1 a and 1 b is illuminated with light polarized into and out of the page (vertically), so it is nominally an s-polarized beam with respect to the PBS. The vertical direction will be referred to in the future as the y direction, and the direction of light propagation will be referred to as the z direction. The color prism 36 depicted is a so-called Philips Prism. However, the detailed results are expected to be independent of the precise color prism configuration.

The y-polarized light incident on the PBS from the lamp, 12, is reflected by the PBS into the color prism. The color prism is shown with its reflecting planes for red and blue light rotated about an axis parallel to that about which the PBS is rotated (parallel to the y-axis). The configuration shown will be referred to as an “s-oriented” color prism.

The other case to be considered is that where the color prism is rotated by 90 degrees about the direction of propagation of the central ray of light through the color prism. In this case the inclined color reflecting surfaces are rotated about an axis perpendicular to that of the PBS rotation axis, which will be referred to as a “p-oriented” color prism.

Wide-angle, high-extinction MacNeille PBS and color prism systems are offered for sale, but are generally designed only to work at ƒ/2.8 and higher. Experimental results using such a MacNeille PBS at ƒ/2 with no color prism and with simulated perfect imagers, yielded only 80:1 contrast. In the present exemplary experimental setup, the simulated perfect imager consisted of a first surface mirror simulating a dark state and a quarter wave film (“QWF”) laminated to mirror and rotated so that its optic axis was 45 degrees to the incident polarization simulating the bright state. It therefore seems unlikely that contrast at acceptable levels (exceeding 250:1 for perfect imagers, so that system contrast with actual imagers will be adequate) could be possible once the color prism is inserted.

However, the Cartesian PBS and color prism of the present invention are specifically designed to be used together in a system. The design assumes that the PBS and the color prism are oriented to have their reflective planes rotated about parallel axes. In general, it was found that known previous systems had been designed with the PBS and the color prism having parallel tilt axes for their reflecting surfaces. Such an arrangement appears to have been chosen because the rays that have highest contrast are those propagating within the plane defined by the normal to the reflecting surface and the optical axis (i.e., the reflection plane of the central ray), whether for a PBS or for a color selective surface. Thus, for conventional components with narrow bands of high contrast situated near the reflection plane of the central ray, (the so-called Maltese bands) perpendicular tilt axes result in a very small region of high contrast, defined by the overlap of the high contrast band of the PBS and the perpendicular high contrast band of the color prism. The amount of light contained in this very small region of angle space is inadequate to provide acceptable contrast at usefully small ƒ/#'s, and so this configuration has never been selected by designers using conventional components.

For the Cartesian PBS, it was found that the band of high contrast for rays reflected from the PBS surface is so broad and the inherent contrast is so good that contrast degradation due to crossing of the tilt axes of the PBS and the color prism is very small. Indeed, in some cases, it is not apparent from the data that there is any inherent degradation in contrast, though it was initially expected for such degradation to be easily noticeable. The performance of the components and system will be demonstrated through the examples below.

Example 1 Performance of APF Cartesian PBS with No Color Prism

Data was first taken to establish the baseline performance of the APF PBS, the mirror simulation of an imager in its dark state, and the mirror with quarter wave film simulation of an imager in its bright state, along with the overall contrast capability of the system of FIGS. 1 a and 1 b (without a color prism). The resulting data is shown in FIGS. 3 and 4 for two different samples of APF Cartesian PBS. The data indicates a very high level of contrast even vis-a-vis the earlier reported performance of plate-type Cartesian PBS systems. FIG. 3 shows the results as a function of wavelength of light at ƒ/2, while FIG. 4 indicates results as a function of ƒ/#. In both cases, the PBS film was contained in a cubic prism made of BK7 glass. In FIG. 4, the data was taken both with and without an optional clean-up polarizer just before the projection lens, to remove stray light due to a slight haze in the PBS prism. The optional clean-up polarizer is not present for the data in FIG. 3. These contrast levels indicate that the optical system itself, including the PBS but not the color prism, has a dark state which presents less than 0.1% of the light present in the bright state.

Example 2 Performance of APF Cartesian PBS and Color Prism with Parallel Tilt Axes

If the color prism is added to the system, but the imagers continue to be simulated by mirrors and quarter wave films as before, then the effects of the depolarization cascade may be assessed. To evaluate these effects, the color prism was designed to work optimally with light that is perfectly y-polarized. The color prism was designed for use at ƒ/#'s down to 2.8, with the PBS and the color prism having parallel tilt axes. Versions of the color prism made of BK7 and of SK5 glass have been used in this work, but the present example focuses on the BK7 glass prism, which has an index of refraction matching that used in the design work. It is important to note, that the color prism was designed to work with perfectly y-polarized light, such as that presented by a Cartesian polarizer. It was specifically not designed to compensate the polarization impurities introduced by a MacNeille PBS. (Designing the color prism to ameliorate the angle dependent phase and rotation of the polarization state of the light introduced by the MacNeille polarizer will degrade the performance of a system using a Cartesian PBS. Similarly, a color separation and recombination prism designed to work well with a Cartesian PBS will perform poorly with a MacNeille PBS.) Accordingly, the use of a Cartesian PBS simplifies color prism design by removing the necessity for such compensation.

FIG. 5 a shows the results of placing the color prism and APF PBS in the system of FIGS. 1 a and 1 b with parallel tilt axes. In taking data for this figure a “notch filter” has been used to block light from the low contrast yellow and cyan regions. (The spectral regions have low contrast due to the effects of band edges in the color separating coatings on the phase of light near the band edges). FIG. 5 b shows the dark and light state irradiance in the same arbitrary units. The photopic contrast ratio is 389:1.

FIG. 6 shows the Maltese band of the dark state for the system configuration of FIGS. 5 a and 5 b, and FIG. 7 shows (for comparison) the same Maltese band for the APF with no color prism. For parallel tilt axes, the Maltese band of the color prism overlays and is parallel to that of the PBS. This reduces the width of the resulting Maltese band, resulting in a decrease in the contrast ratio between the configuration used in FIGS. 3 and 4 without a color prism, and that used for FIGS. 5 a and 5 b with a color prism.

The degradation of contrast outside the relatively narrow region around the reflection plane of the central ray may be attributed to the color prism. This is evident from FIG. 7, which shows the equivalent pupil image when the color prism is removed. The digital camera used for these images automatically re-scales the brightness of the image, so direct comparisons between the two figures is not possible. However, the contrast ratio for the configuration of FIG. 7 is about six times that for FIG. 6, meaning that this dark state pupil image is six times darker than FIG. 6.

Example 3 Performance of APF Cartesian PBS and Color Prism with Perpendicular Tilt Axes

Because the Maltese band for the PBS itself is so deep and broad, we expect that there may be a minimal degradation in contrast resulting from the crossing of the Maltese band due to the color prism with that due to the PBS. In this case, rather than figuratively overlaying the narrow horizontal Maltese band of the color prism over the broad horizontal Maltese band of the PBS, a vertical Maltese band is overlayed due to the color prism cross-wise over the broad horizontal Maltese band of the PBS. Due to the extremely broad nature of the Maltese band of the APF PBS (the pupil image contains rays with polar angles out to about 14°) the degradation in contrast resulting from this crossing of bands is small. This is quite different from the case for conventional MacNeille PBS components.

FIG. 8 a demonstrates the performance obtained when the color prism is rotated so that s-polarized light from the PBS became p-polarized relative to the inclined surfaces of the color prism. It is clear that the contrast is somewhat lower than in FIG. 5 a, but the reduction is quite small, only about 15% (301:1 vs. 360:1). In addition, because a high pressure Hg lamp was used, and because these lamps present a non-uniform, peaked spectral intensity function (as can be seen in FIGS. 5 b and 8 b) the photopic contrast is quite sensitive to the precise wavelengths at which the color prism coatings provide the best contrast.

The peaked nature of the spectral intensity function of the lamp makes final system performance very sensitive to small variations in the spectral contrast performance of the color prism. It is therefore essential to refine the color prism design to ensure that peak spectral contrast wavelength remains at the spectral peaks of lamp intensity after rotating the prism tilt axes so that they are not parallel to that of the PBS. FIG. 9 depicts the Maltese band for the perpendicular tilt axes configuration. In keeping with the minimal contrast ratio differences seen between FIGS. 5 a and 8 a, this image looks much like that of FIG. 6, rotated by 90°.

Claims (16)

1. A projection system comprising:
a) a Cartesian polarizing beam splitter, the Cartesian polarizing beam splitter defining a first tilt axis perpendicular to a first reflection plane;
b) a color separation prism assembly, the prism assembly having a second tilt axis perpendicular to a second reflection plane;
c) wherein the Cartesian polarizing beam splitter and the prism assembly are arranged such that the first and the second reflection planes are perpendicular to each other.
2. The projection system of claim 1, further comprising an illumination system providing a beam of light, the illumination system having an f/# less than or equal to 2.5.
3. The projection system of claim 1, wherein the projection system is a front projection system.
4. The projection system of claim 1, wherein the system is a rear projection system.
5. The projection system of claim 1, wherein the color separation prism assembly includes a Philips prism.
6. The projection system of claim 1, wherein the Cartesian polarizing beam splitter includes a multilayer optical film.
7. The projection system of claim 1, wherein the Cartesian polarizing beamsplitter is disposed so that illumination light reaching the color separation prism assembly via the Cartesian polarizing beamsplitter is in substantially the same polarization state across all color bands.
8. A projection system comprising:
(a) a polarizing beam splitter, the polarizing beam splitter defining a first tilt axis perpendicular to a first reflection plane; and
(b) a color prism assembly, the color prism assembly having a second tilt axis perpendicular to a second reflection plane, the polarizing beam splitter and the prism assembly being arranged so that the first reflection plane is perpendicular to the second reflection plane.
9. The system as recited in claim 8, wherein the polarizing bean splitter comprises a Cartesian polarizing beam splitter.
10. The system as recited in claim 8, further comprising an illumination system capable of providing a beam of light incident at the polarizing beamsplitter, the illumination system having an f-number less than or equal to 2.5.
11. The system of claim 8, wherein the projection system is a front projection system.
12. The system of claim 8, wherein the system is a rear projection system.
13. The system of claim 8, wherein the prism assembly comprises a Philips prism.
14. The system of claim 8, wherein the polarizing beam splitter comprises a multilayer optical film disposed between two prisms.
15. The system claim 8, further comprising a plurality of imagers, the color prism assembly having a plurality of transmissive surfaces and each imager of the plurality of imagers being aligned with respect to a corresponding transmissive surface of the prism assembly.
16. The system of claim 8, wherein the first tilt axis is perpendicular to the first reflection plane defined by a light ray incident at the polarizing beam splitter and a normal to a reflecting surface of the polarizing beamsplitter and the second tilt axis is perpendicular to the second reflection plane defined by a light ray incident at the color prism assembly and a normal to a reflection surface of the color prism assembly.
US11315721 1993-12-21 2005-12-22 Reflective LCD projection system using wide-angle cartesian polarizing beam splitter and color separation and recombination prisms Expired - Fee Related US7652820B2 (en)

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US08958329 US5965247A (en) 1993-12-21 1997-10-28 Process for forming reflective polarizer
US12691798 true 1998-07-31 1998-07-31
US09312917 US6486997B1 (en) 1997-10-28 1999-05-17 Reflective LCD projection system using wide-angle Cartesian polarizing beam splitter
US17897300 true 2000-01-25 2000-01-25
US09746933 US7023602B2 (en) 1999-05-17 2000-12-22 Reflective LCD projection system using wide-angle Cartesian polarizing beam splitter and color separation and recombination prisms
US11315721 US7652820B2 (en) 1997-10-28 2005-12-22 Reflective LCD projection system using wide-angle cartesian polarizing beam splitter and color separation and recombination prisms

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080285129A1 (en) * 2007-05-18 2008-11-20 3M Innovative Properties Company Color light combining system for optical projector

Families Citing this family (51)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0962806B1 (en) 1993-12-21 2008-12-03 Minnesota Mining And Manufacturing Company Multilayered optical film
US7023602B2 (en) * 1999-05-17 2006-04-04 3M Innovative Properties Company Reflective LCD projection system using wide-angle Cartesian polarizing beam splitter and color separation and recombination prisms
US6672721B2 (en) * 2001-06-11 2004-01-06 3M Innovative Properties Company Projection system having low astigmatism
US6795243B1 (en) * 2001-10-05 2004-09-21 Optical Coating Laboratory, Inc. Polarizing light pipe
EP1461962A1 (en) * 2002-01-07 2004-09-29 3M Innovative Properties Company Color component aperture stops in projection display system
US7008065B2 (en) 2003-01-07 2006-03-07 3M Innovative Properties Company Color component aperture stops in projection display system
US6634756B1 (en) * 2002-06-27 2003-10-21 Koninklijke Philips Electronics N.V. Beam-splitter folded path for rear projection displays
KR20040072424A (en) * 2003-02-12 2004-08-18 엘지전자 주식회사 projection-type optical system of thin-type
US6857752B2 (en) * 2003-04-11 2005-02-22 3M Innovative Properties Company Projection illumination system with tunnel integrator and field lens
US7639208B1 (en) * 2004-05-21 2009-12-29 University Of Central Florida Research Foundation, Inc. Compact optical see-through head-mounted display with occlusion support
US7327408B1 (en) * 2004-11-15 2008-02-05 Lightmaster Systems, Inc. Illuminator that generates linearly polarized light for microdisplay based light engine
US7570424B2 (en) 2004-12-06 2009-08-04 Moxtek, Inc. Multilayer wire-grid polarizer
US7800823B2 (en) 2004-12-06 2010-09-21 Moxtek, Inc. Polarization device to polarize and further control light
US7961393B2 (en) 2004-12-06 2011-06-14 Moxtek, Inc. Selectively absorptive wire-grid polarizer
US7359122B2 (en) * 2005-06-09 2008-04-15 Hewlett-Packard Development Company, L.P. Prism assembly
JP2009507256A (en) * 2005-09-02 2009-02-19 カラーリンク・インコーポレイテッドColorlink, Inc. Polarizing beam splitters and combiners
US20070296921A1 (en) * 2006-06-26 2007-12-27 Bin Wang Projection display with a cube wire-grid polarizing beam splitter
US8755113B2 (en) 2006-08-31 2014-06-17 Moxtek, Inc. Durable, inorganic, absorptive, ultra-violet, grid polarizer
US8369442B2 (en) * 2007-01-12 2013-02-05 Fujitsu Limited Communicating a signal according to ASK modulation and PSK modulation
US7789515B2 (en) 2007-05-17 2010-09-07 Moxtek, Inc. Projection device with a folded optical path and wire-grid polarizer
US8469515B2 (en) * 2007-12-21 2013-06-25 Seiko Epson Corporation Illuminator, image display apparatus, and polarization conversion/diffusion member
US8087785B2 (en) * 2008-02-25 2012-01-03 Young Optics Inc. Projection display apparatus
US8248696B2 (en) 2009-06-25 2012-08-21 Moxtek, Inc. Nano fractal diffuser
US9826942B2 (en) * 2009-11-25 2017-11-28 Dental Imaging Technologies Corporation Correcting and reconstructing x-ray images using patient motion vectors extracted from marker positions in x-ray images
US9082182B2 (en) * 2009-11-25 2015-07-14 Dental Imaging Technologies Corporation Extracting patient motion vectors from marker positions in x-ray images
US9082036B2 (en) * 2009-11-25 2015-07-14 Dental Imaging Technologies Corporation Method for accurate sub-pixel localization of markers on X-ray images
US9082177B2 (en) * 2009-11-25 2015-07-14 Dental Imaging Technologies Corporation Method for tracking X-ray markers in serial CT projection images
US8363919B2 (en) 2009-11-25 2013-01-29 Imaging Sciences International Llc Marker identification and processing in x-ray images
KR101775746B1 (en) 2010-05-21 2017-09-06 쓰리엠 이노베이티브 프로퍼티즈 컴파니 Partially reflecting multilayer optical films with reduced color
US8611007B2 (en) 2010-09-21 2013-12-17 Moxtek, Inc. Fine pitch wire grid polarizer
US8913321B2 (en) 2010-09-21 2014-12-16 Moxtek, Inc. Fine pitch grid polarizer
US8300160B2 (en) * 2010-09-21 2012-10-30 Hon Hai Precision Industry Co., Ltd. Projector system
US9353930B2 (en) 2011-04-08 2016-05-31 3M Innovative Properties Company Light duct tee extractor
US8913320B2 (en) 2011-05-17 2014-12-16 Moxtek, Inc. Wire grid polarizer with bordered sections
US8873144B2 (en) 2011-05-17 2014-10-28 Moxtek, Inc. Wire grid polarizer with multiple functionality sections
CN103890643B (en) 2011-10-24 2018-01-26 默克专利股份有限公司 Switching element comprising a liquid crystal medium
US8922890B2 (en) 2012-03-21 2014-12-30 Moxtek, Inc. Polarizer edge rib modification
US8830337B2 (en) * 2012-09-04 2014-09-09 Himax Imaging Limited Electronic device with camera functions
JP2016505671A (en) 2012-12-13 2016-02-25 メルク パテント ゲゼルシャフト ミット ベシュレンクテル ハフツングMerck Patent Gesellschaft mit beschraenkter Haftung The liquid-crystal media
KR20150123901A (en) 2013-03-05 2015-11-04 메르크 파텐트 게엠베하 Device for regulating the passage of optical energy
KR20160005116A (en) 2013-05-08 2016-01-13 메르크 파텐트 게엠베하 Device comprising two liquid crystal switching layers for regulating the passage of optical energy
US20160108317A1 (en) 2013-05-24 2016-04-21 Merck Patent Gmbh Device for controlling the passage of energy, containing a dichroic dye compound
US9354374B2 (en) 2013-10-24 2016-05-31 Moxtek, Inc. Polarizer with wire pair over rib
US9841598B2 (en) 2013-12-31 2017-12-12 3M Innovative Properties Company Lens with embedded multilayer optical film for near-eye display systems
JP2016053644A (en) * 2014-09-03 2016-04-14 キヤノン株式会社 Color separation synthesis system and projection type display device
DE102015005800A1 (en) 2015-05-06 2016-11-10 Merck Patent Gmbh Thiadiazolochinoxalinderivate
WO2017008880A1 (en) 2015-07-10 2017-01-19 Merck Patent Gmbh Dithio-alkyl-pyrrolo-pyrroles and use thereof as dyes
CN105425508A (en) * 2015-11-20 2016-03-23 中国空气动力研究与发展中心超高速空气动力研究所 Polarizing and beam-splitting apparatus for sequential laser shadowgraph
EP3260913A1 (en) 2016-06-22 2017-12-27 Merck Patent GmbH Optical switching device
WO2018001919A1 (en) 2016-06-28 2018-01-04 Merck Patent Gmbh Liquid crystalline medium
WO2018015320A1 (en) 2016-07-19 2018-01-25 Merck Patent Gmbh Liquid crystalline medium

Citations (103)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6390626B1 (en) *
US540768A (en) 1895-06-11 Richard walsingham western
US2604817A (en) 1948-10-14 1952-07-29 Du Pont Light polarizing composition
US3124639A (en) 1964-03-10 figure
US3438691A (en) 1964-05-14 1969-04-15 Polaroid Corp Birefringent polarizer
US3508809A (en) * 1967-12-29 1970-04-28 Rca Corp High efficiency light polarization system
US3610729A (en) 1969-06-18 1971-10-05 Polaroid Corp Multilayered light polarizer
US3677621A (en) * 1969-11-24 1972-07-18 Vickers Ltd Optical field flattening devices
US3711176A (en) 1971-01-14 1973-01-16 Dow Chemical Co Highly reflective thermoplastic bodies for infrared, visible or ultraviolet light
US3860036A (en) 1970-11-02 1975-01-14 Dow Chemical Co Variable geometry feed block for multilayer extrusion
US4446305A (en) 1981-03-02 1984-05-01 Polaroid Corporation Optical device including birefringent polymer
US4520189A (en) 1981-03-02 1985-05-28 Polaroid Corporation Optical device including birefringent aromatic amino carboxylic acid polymer
US4521588A (en) 1981-03-02 1985-06-04 Polaroid Corporation Optical device including birefringent polyhydrazide polymer
US4525413A (en) 1981-03-02 1985-06-25 Polaroid Corporation Optical device including birefringent polymer
US4720426A (en) 1986-06-30 1988-01-19 General Electric Company Reflective coating for solid-state scintillator bar
US4723077A (en) 1985-12-06 1988-02-02 Hughes Aircraft Company Dual liquid crystal light valve based visible-to-infrared dynamic image converter system
GB2177814B (en) 1985-07-11 1989-08-23 Coherent Inc Polarization preserving reflector and method
US4943154A (en) 1988-02-25 1990-07-24 Matsushita Electric Industrial Co., Ltd. Projection display apparatus
US4943155A (en) 1987-12-22 1990-07-24 Hughes Aircraft Company Color projection system with a color correction wedge
EP0422661A2 (en) 1989-10-13 1991-04-17 Mitsubishi Rayon Co., Ltd Polarization forming optical device and polarization beam splitter
US5042921A (en) 1988-10-25 1991-08-27 Casio Computer Co., Ltd. Liquid crystal display apparatus
EP0488544A1 (en) 1990-11-26 1992-06-03 The Dow Chemical Company Birefringent interference polarizer
US5122905A (en) 1989-06-20 1992-06-16 The Dow Chemical Company Relective polymeric body
EP0492636A1 (en) 1990-12-27 1992-07-01 Canon Kabushiki Kaisha Polarization illumination device and projector having the same
US5146248A (en) 1987-12-23 1992-09-08 North American Philips Corporation Light valve projection system with improved illumination
US5188760A (en) 1990-04-06 1993-02-23 U. S. Philips Corporation Liquid crystalline material and display cell containing said material
US5200843A (en) 1989-10-05 1993-04-06 Seiko Epson Corporation Polarized synthesization in projection type liquid crystal displays
US5210548A (en) 1991-08-01 1993-05-11 Xerox Corporation Method and system for reducing surface reflections from a photosensitive imaging member
US5211878A (en) 1988-03-10 1993-05-18 Merck Patent Gesellschaft Mit Beschrankter Haftung Difluorobenzonitrile derivatives
US5217794A (en) 1991-01-22 1993-06-08 The Dow Chemical Company Lamellar polymeric body
US5233465A (en) 1992-05-27 1993-08-03 The Dow Chemical Company Visibly transparent infrared reflecting film with color masking
US5235443A (en) 1989-07-10 1993-08-10 Hoffmann-La Roche Inc. Polarizer device
EP0568998A2 (en) 1992-05-06 1993-11-10 Canon Kabushiki Kaisha Image forming apparatus and projector using the same
US5269995A (en) 1992-10-02 1993-12-14 The Dow Chemical Company Coextrusion of multilayer articles using protective boundary layers and apparatus therefor
US5294657A (en) 1992-05-15 1994-03-15 Melendy Peter S Adhesive composition with decorative glitter
US5295018A (en) 1991-03-04 1994-03-15 Hitachi, Ltd. Polarization transforming optics, polarizing beam splitter and liquid crystal display
US5303083A (en) 1992-08-26 1994-04-12 Hughes Aircraft Company Polarized light recovery
US5319478A (en) 1989-11-01 1994-06-07 Hoffmann-La Roche Inc. Light control systems with a circular polarizer and a twisted nematic liquid crystal having a minimum path difference of λ/2
US5321683A (en) 1992-12-28 1994-06-14 Eastman Kodak Company Digital optical tape read system
EP0606940A2 (en) 1993-01-11 1994-07-20 Philips Electronics N.V. Chloresteric polarizer and the manufacture thereof
US5371559A (en) 1991-11-15 1994-12-06 Matsushita Electric Industrial Co., Ltd. Light valve image projection apparatus
US5379083A (en) 1994-02-15 1995-01-03 Raychem Corporation Projector
US5389324A (en) 1993-06-07 1995-02-14 The Dow Chemical Company Layer thickness gradient control in multilayer polymeric bodies
US5448404A (en) 1992-10-29 1995-09-05 The Dow Chemical Company Formable reflective multilayer body
US5486935A (en) 1993-06-29 1996-01-23 Kaiser Aerospace And Electronics Corporation High efficiency chiral nematic liquid crystal rear polarizer for liquid crystal displays having a notch polarization bandwidth of 100 nm to 250 nm
EP0718645A2 (en) 1994-12-19 1996-06-26 Sharp Kabushiki Kaisha Optical device and head-mounted display using said optical device
US5594563A (en) 1994-05-31 1997-01-14 Honeywell Inc. High resolution subtractive color projection system
US5621486A (en) 1995-06-22 1997-04-15 International Business Machines Corporation Efficient optical system for a high resolution projection display employing reflection light valves
US5629055A (en) 1994-02-14 1997-05-13 Pulp And Paper Research Institute Of Canada Solidified liquid crystals of cellulose with optically variable properties
US5686979A (en) 1995-06-26 1997-11-11 Minnesota Mining And Manufacturing Company Optical panel capable of switching between reflective and transmissive states
US5699188A (en) 1995-06-26 1997-12-16 Minnesota Mining And Manufacturing Co. Metal-coated multilayer mirror
US5721603A (en) 1993-01-11 1998-02-24 U.S. Philips Corporation Illumination system and display device including such a system
EP0837351A2 (en) 1996-10-17 1998-04-22 Compaq Computer Corporation Projection display apparatus
US5744534A (en) 1992-08-10 1998-04-28 Bridgestone Corporation Light scattering material
US5751388A (en) 1995-04-07 1998-05-12 Honeywell Inc. High efficiency polarized display
US5767935A (en) 1995-08-31 1998-06-16 Sumitomo Chemical Company, Limited Light control sheet and liquid crystal display device comprising the same
US5770306A (en) 1995-03-09 1998-06-23 Dai Nippon Printing Co., Ltd. Antireflection film containing ultrafine particles, polarizing plate and liquid crystal display device
US5783120A (en) 1996-02-29 1998-07-21 Minnesota Mining And Manufacturing Company Method for making an optical film
US5808794A (en) 1996-07-31 1998-09-15 Weber; Michael F. Reflective polarizers having extended red band edge for controlled off axis color
US5825543A (en) 1996-02-29 1998-10-20 Minnesota Mining And Manufacturing Company Diffusely reflecting polarizing element including a first birefringent phase and a second phase
US5825542A (en) 1995-06-26 1998-10-20 Minnesota Mining And Manufacturing Company Diffusely reflecting multilayer polarizers and mirrors
US5867316A (en) 1996-02-29 1999-02-02 Minnesota Mining And Manufacturing Company Multilayer film having a continuous and disperse phase
US5882774A (en) 1993-12-21 1999-03-16 Minnesota Mining And Manufacturing Company Optical film
US5940149A (en) 1997-12-11 1999-08-17 Minnesota Mining And Manufacturing Company Planar polarizer for LCD projectors
US5976424A (en) 1996-07-31 1999-11-02 Minnesota Mining And Manufacturing Company Method for making multilayer optical films having thin optical layers
US5999317A (en) 1998-01-13 1999-12-07 3M Innovative Properties Company Toy mirror with transmissive image mode
US5999316A (en) 1997-12-06 1999-12-07 3M Innovative Properties Company Light valve with rotating polarizing element
US6012820A (en) 1998-01-13 2000-01-11 3M Innovative Properties Compnay Lighted hand-holdable novelty article
US6025897A (en) 1993-12-21 2000-02-15 3M Innovative Properties Co. Display with reflective polarizer and randomizing cavity
US6024455A (en) 1998-01-13 2000-02-15 3M Innovative Properties Company Reflective article with concealed retroreflective pattern
US6045894A (en) 1998-01-13 2000-04-04 3M Innovative Properties Company Clear to colored security film
US6049419A (en) 1998-01-13 2000-04-11 3M Innovative Properties Co Multilayer infrared reflecting optical body
US6053795A (en) 1998-01-13 2000-04-25 3M Innovative Properties Company Toy having image mode and changed image mode
US6072629A (en) 1997-02-26 2000-06-06 Reveo, Inc. Polarizer devices and methods for making the same
US6080467A (en) 1995-06-26 2000-06-27 3M Innovative Properties Company High efficiency optical devices
US6082876A (en) 1998-01-13 2000-07-04 3M Innovative Properties Company Hand-holdable toy light tube with color changing film
US6088067A (en) 1995-06-26 2000-07-11 3M Innovative Properties Company Liquid crystal display projection system using multilayer optical film polarizers
US6096375A (en) 1993-12-21 2000-08-01 3M Innovative Properties Company Optical polarizer
US6096247A (en) 1998-07-31 2000-08-01 3M Innovative Properties Company Embossed optical polymer films
US6101032A (en) 1994-04-06 2000-08-08 3M Innovative Properties Company Light fixture having a multilayer polymeric film
US6111697A (en) 1998-01-13 2000-08-29 3M Innovative Properties Company Optical device with a dichroic polarizer and a multilayer optical film
US6113811A (en) 1998-01-13 2000-09-05 3M Innovative Properties Company Dichroic polarizing film and optical polarizer containing the film
US6120026A (en) 1998-01-13 2000-09-19 3M Innovative Properties Co. Game with privacy material
US6124971A (en) 1995-06-26 2000-09-26 3M Innovative Properties Company Transflective displays with reflective polarizing transflector
US6157486A (en) 1998-01-13 2000-12-05 3M Innovative Properties Company Retroreflective dichroic reflector
US6157490A (en) 1998-01-13 2000-12-05 3M Innovative Properties Company Optical film with sharpened bandedge
US6160663A (en) 1998-10-01 2000-12-12 3M Innovative Properties Company Film confined to a frame having relative anisotropic expansion characteristics
US6179948B1 (en) 1998-01-13 2001-01-30 3M Innovative Properties Company Optical film and process for manufacture thereof
US6207260B1 (en) 1998-01-13 2001-03-27 3M Innovative Properties Company Multicomponent optical body
US6208466B1 (en) 1998-11-25 2001-03-27 3M Innovative Properties Company Multilayer reflector with selective transmission
US6256146B1 (en) 1998-07-31 2001-07-03 3M Innovative Properties Post-forming continuous/disperse phase optical bodies
US6288172B1 (en) 1995-06-26 2001-09-11 3M Innovative Properties Company Light diffusing adhesive
US6322236B1 (en) 1999-02-09 2001-11-27 3M Innovative Properties Company Optical film with defect-reducing surface and method for making same
US6352761B1 (en) 1998-01-13 2002-03-05 3M Innovative Properties Company Modified copolyesters and improved multilayer reflective films
US6368699B1 (en) 1995-06-26 2002-04-09 3M Innovative Properties Company Multilayer polymer film with additional coatings or layers
US6486997B1 (en) 1997-10-28 2002-11-26 3M Innovative Properties Company Reflective LCD projection system using wide-angle Cartesian polarizing beam splitter
US6515785B1 (en) 1999-04-22 2003-02-04 3M Innovative Properties Company Optical devices using reflecting polarizing materials
US6531230B1 (en) 1998-01-13 2003-03-11 3M Innovative Properties Company Color shifting film
US6565982B1 (en) 1995-06-26 2003-05-20 3M Innovative Properties Company Transparent multilayer device
US6569515B2 (en) 1998-01-13 2003-05-27 3M Innovative Properties Company Multilayered polymer films with recyclable or recycled layers
US6609795B2 (en) 2001-06-11 2003-08-26 3M Innovative Properties Company Polarizing beam splitter
US6672721B2 (en) * 2001-06-11 2004-01-06 3M Innovative Properties Company Projection system having low astigmatism
US7023602B2 (en) 1999-05-17 2006-04-04 3M Innovative Properties Company Reflective LCD projection system using wide-angle Cartesian polarizing beam splitter and color separation and recombination prisms

Family Cites Families (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3508808A (en) * 1969-04-04 1970-04-28 Bunker Ramo Digit light deflector
US4425028A (en) * 1981-12-28 1984-01-10 Hughes Aircraft Company High efficiency optical tank for three color liquid crystal light valve image projection with color selective prepolarization and single projection lens
US4511220A (en) * 1982-12-23 1985-04-16 The United States Of America As Represented By The Secretary Of The Air Force Laser target speckle eliminator
JP2505758B2 (en) * 1986-08-04 1996-06-12 キヤノン株式会社 Video Puroji Ekushi Yon equipment
US5200848A (en) * 1987-09-17 1993-04-06 Canon Kabushiki Kaisha Ferroelectric smectic liquid crystal device
JPH03288124A (en) * 1990-04-04 1991-12-18 Victor Co Of Japan Ltd Optical system of color image display device
US5644432A (en) * 1995-01-17 1997-07-01 Ibm Corporation Three prism color separator
DE69611561D1 (en) * 1995-03-23 2001-02-22 Ibm Effective optical system for a high-resolution projection display with reflection light valves
JP3290091B2 (en) * 1997-03-31 2002-06-10 シャープ株式会社 Projection-type image display device
US6052214A (en) * 1998-01-23 2000-04-18 Chuang; Chih-Li System and method for producing an enhanced image
US5986815A (en) * 1998-05-15 1999-11-16 Optical Coating Laboratory, Inc. Systems, methods and apparatus for improving the contrast ratio in reflective imaging systems utilizing color splitters
US6304302B1 (en) * 1998-05-26 2001-10-16 Industrial Technology Research Institute Liquid crystal display system and light projection system
US6144498A (en) * 1998-06-11 2000-11-07 Optical Coating Laboratory, Inc. Color separation prism assembly and method for making same
WO2000002087A1 (en) * 1998-07-02 2000-01-13 Koninklijke Philips Electronics N.V. Image projection system
US6172816B1 (en) * 1998-10-23 2001-01-09 Duke University Optical component adjustment for mitigating tolerance sensitivities
US6398364B1 (en) * 1999-10-06 2002-06-04 Optical Coating Laboratory, Inc. Off-axis image projection display system

Patent Citations (129)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6390626B1 (en) *
US540768A (en) 1895-06-11 Richard walsingham western
US3124639A (en) 1964-03-10 figure
US2604817A (en) 1948-10-14 1952-07-29 Du Pont Light polarizing composition
US3438691A (en) 1964-05-14 1969-04-15 Polaroid Corp Birefringent polarizer
US3508809A (en) * 1967-12-29 1970-04-28 Rca Corp High efficiency light polarization system
US3610729A (en) 1969-06-18 1971-10-05 Polaroid Corp Multilayered light polarizer
US3677621A (en) * 1969-11-24 1972-07-18 Vickers Ltd Optical field flattening devices
US3860036A (en) 1970-11-02 1975-01-14 Dow Chemical Co Variable geometry feed block for multilayer extrusion
US3711176A (en) 1971-01-14 1973-01-16 Dow Chemical Co Highly reflective thermoplastic bodies for infrared, visible or ultraviolet light
US4446305A (en) 1981-03-02 1984-05-01 Polaroid Corporation Optical device including birefringent polymer
US4520189A (en) 1981-03-02 1985-05-28 Polaroid Corporation Optical device including birefringent aromatic amino carboxylic acid polymer
US4521588A (en) 1981-03-02 1985-06-04 Polaroid Corporation Optical device including birefringent polyhydrazide polymer
US4525413A (en) 1981-03-02 1985-06-25 Polaroid Corporation Optical device including birefringent polymer
GB2177814B (en) 1985-07-11 1989-08-23 Coherent Inc Polarization preserving reflector and method
US4723077A (en) 1985-12-06 1988-02-02 Hughes Aircraft Company Dual liquid crystal light valve based visible-to-infrared dynamic image converter system
US4720426A (en) 1986-06-30 1988-01-19 General Electric Company Reflective coating for solid-state scintillator bar
US4943155A (en) 1987-12-22 1990-07-24 Hughes Aircraft Company Color projection system with a color correction wedge
US5146248A (en) 1987-12-23 1992-09-08 North American Philips Corporation Light valve projection system with improved illumination
US4943154A (en) 1988-02-25 1990-07-24 Matsushita Electric Industrial Co., Ltd. Projection display apparatus
US5211878A (en) 1988-03-10 1993-05-18 Merck Patent Gesellschaft Mit Beschrankter Haftung Difluorobenzonitrile derivatives
US5042921A (en) 1988-10-25 1991-08-27 Casio Computer Co., Ltd. Liquid crystal display apparatus
US5612820A (en) 1989-06-20 1997-03-18 The Dow Chemical Company Birefringent interference polarizer
US5122905A (en) 1989-06-20 1992-06-16 The Dow Chemical Company Relective polymeric body
US5486949A (en) 1989-06-20 1996-01-23 The Dow Chemical Company Birefringent interference polarizer
US5122906A (en) 1989-06-20 1992-06-16 The Dow Chemical Company Thick/very thin multilayer reflective polymeric body
US5235443A (en) 1989-07-10 1993-08-10 Hoffmann-La Roche Inc. Polarizer device
US5200843A (en) 1989-10-05 1993-04-06 Seiko Epson Corporation Polarized synthesization in projection type liquid crystal displays
US5278680A (en) 1989-10-05 1994-01-11 Seiko Epson Corporation Projection type liquid crystal display system and method of polarized light component projection
EP0422661A2 (en) 1989-10-13 1991-04-17 Mitsubishi Rayon Co., Ltd Polarization forming optical device and polarization beam splitter
US5319478A (en) 1989-11-01 1994-06-07 Hoffmann-La Roche Inc. Light control systems with a circular polarizer and a twisted nematic liquid crystal having a minimum path difference of λ/2
US5188760A (en) 1990-04-06 1993-02-23 U. S. Philips Corporation Liquid crystalline material and display cell containing said material
EP0488544A1 (en) 1990-11-26 1992-06-03 The Dow Chemical Company Birefringent interference polarizer
EP0488544B1 (en) 1990-11-26 1998-01-07 The Dow Chemical Company Birefringent interference polarizer
EP0492636A1 (en) 1990-12-27 1992-07-01 Canon Kabushiki Kaisha Polarization illumination device and projector having the same
US5316703A (en) 1991-01-22 1994-05-31 The Dow Chemical Company Method of producing a lamellar polymeric body
US5217794A (en) 1991-01-22 1993-06-08 The Dow Chemical Company Lamellar polymeric body
US5295018A (en) 1991-03-04 1994-03-15 Hitachi, Ltd. Polarization transforming optics, polarizing beam splitter and liquid crystal display
US5210548A (en) 1991-08-01 1993-05-11 Xerox Corporation Method and system for reducing surface reflections from a photosensitive imaging member
US5371559A (en) 1991-11-15 1994-12-06 Matsushita Electric Industrial Co., Ltd. Light valve image projection apparatus
US5580142A (en) 1992-05-06 1996-12-03 Canon Kabushiki Kaisha Image forming apparatus and projector using the same
EP0568998A2 (en) 1992-05-06 1993-11-10 Canon Kabushiki Kaisha Image forming apparatus and projector using the same
US5294657A (en) 1992-05-15 1994-03-15 Melendy Peter S Adhesive composition with decorative glitter
US5233465A (en) 1992-05-27 1993-08-03 The Dow Chemical Company Visibly transparent infrared reflecting film with color masking
US5744534A (en) 1992-08-10 1998-04-28 Bridgestone Corporation Light scattering material
US5303083A (en) 1992-08-26 1994-04-12 Hughes Aircraft Company Polarized light recovery
US5269995A (en) 1992-10-02 1993-12-14 The Dow Chemical Company Coextrusion of multilayer articles using protective boundary layers and apparatus therefor
US5448404A (en) 1992-10-29 1995-09-05 The Dow Chemical Company Formable reflective multilayer body
US5321683A (en) 1992-12-28 1994-06-14 Eastman Kodak Company Digital optical tape read system
US5793456A (en) 1993-01-11 1998-08-11 U.S. Philips Corporation Cholesteric polarizer and the manufacture thereof
US5721603A (en) 1993-01-11 1998-02-24 U.S. Philips Corporation Illumination system and display device including such a system
EP0606940A2 (en) 1993-01-11 1994-07-20 Philips Electronics N.V. Chloresteric polarizer and the manufacture thereof
US5389324A (en) 1993-06-07 1995-02-14 The Dow Chemical Company Layer thickness gradient control in multilayer polymeric bodies
US5486935A (en) 1993-06-29 1996-01-23 Kaiser Aerospace And Electronics Corporation High efficiency chiral nematic liquid crystal rear polarizer for liquid crystal displays having a notch polarization bandwidth of 100 nm to 250 nm
US6296927B1 (en) 1993-12-21 2001-10-02 3M Innovative Properties Optical film
US6117530A (en) 1993-12-21 2000-09-12 3M Innovative Properties Company Optical film
US5965247A (en) 1993-12-21 1999-10-12 3M Innovative Properties Company Process for forming reflective polarizer
US7083847B2 (en) 1993-12-21 2006-08-01 3M Innovative Properties Company Optical film
US6613421B2 (en) 1993-12-21 2003-09-02 3M Innovative Properties Company Optical film
US5962114A (en) 1993-12-21 1999-10-05 3M Innovative Properties Company Polarizing beam-splitting optical component
US6096375A (en) 1993-12-21 2000-08-01 3M Innovative Properties Company Optical polarizer
US5882774A (en) 1993-12-21 1999-03-16 Minnesota Mining And Manufacturing Company Optical film
US6635337B2 (en) 1993-12-21 2003-10-21 3M Innovative Properties Company Optical film
US6025897A (en) 1993-12-21 2000-02-15 3M Innovative Properties Co. Display with reflective polarizer and randomizing cavity
US5629055A (en) 1994-02-14 1997-05-13 Pulp And Paper Research Institute Of Canada Solidified liquid crystals of cellulose with optically variable properties
US5379083A (en) 1994-02-15 1995-01-03 Raychem Corporation Projector
US6101032A (en) 1994-04-06 2000-08-08 3M Innovative Properties Company Light fixture having a multilayer polymeric film
US5594563A (en) 1994-05-31 1997-01-14 Honeywell Inc. High resolution subtractive color projection system
EP0718645A2 (en) 1994-12-19 1996-06-26 Sharp Kabushiki Kaisha Optical device and head-mounted display using said optical device
US5770306A (en) 1995-03-09 1998-06-23 Dai Nippon Printing Co., Ltd. Antireflection film containing ultrafine particles, polarizing plate and liquid crystal display device
US5751388A (en) 1995-04-07 1998-05-12 Honeywell Inc. High efficiency polarized display
US5621486A (en) 1995-06-22 1997-04-15 International Business Machines Corporation Efficient optical system for a high resolution projection display employing reflection light valves
US6368699B1 (en) 1995-06-26 2002-04-09 3M Innovative Properties Company Multilayer polymer film with additional coatings or layers
US5825542A (en) 1995-06-26 1998-10-20 Minnesota Mining And Manufacturing Company Diffusely reflecting multilayer polarizers and mirrors
US5699188A (en) 1995-06-26 1997-12-16 Minnesota Mining And Manufacturing Co. Metal-coated multilayer mirror
US6088163A (en) 1995-06-26 2000-07-11 3M Innovative Properties Company Metal-coated multilayer mirror
US6080467A (en) 1995-06-26 2000-06-27 3M Innovative Properties Company High efficiency optical devices
US6288172B1 (en) 1995-06-26 2001-09-11 3M Innovative Properties Company Light diffusing adhesive
US5686979A (en) 1995-06-26 1997-11-11 Minnesota Mining And Manufacturing Company Optical panel capable of switching between reflective and transmissive states
US6018419A (en) 1995-06-26 2000-01-25 3M Intellectual Properties Company Diffuse reflectors
US6124971A (en) 1995-06-26 2000-09-26 3M Innovative Properties Company Transflective displays with reflective polarizing transflector
US6565982B1 (en) 1995-06-26 2003-05-20 3M Innovative Properties Company Transparent multilayer device
US6088067A (en) 1995-06-26 2000-07-11 3M Innovative Properties Company Liquid crystal display projection system using multilayer optical film polarizers
US5767935A (en) 1995-08-31 1998-06-16 Sumitomo Chemical Company, Limited Light control sheet and liquid crystal display device comprising the same
US6031665A (en) 1996-02-29 2000-02-29 3M Innovative Properties Company Method of forming a multilayer film having a continuous and disperse phase
US6297906B1 (en) 1996-02-29 2001-10-02 3M Innovative Properties Company Light fixture containing optical film
US6057961A (en) 1996-02-29 2000-05-02 3M Innovative Properties Company Optical film with increased gain at non-normal angles of incidence
US5867316A (en) 1996-02-29 1999-02-02 Minnesota Mining And Manufacturing Company Multilayer film having a continuous and disperse phase
US5825543A (en) 1996-02-29 1998-10-20 Minnesota Mining And Manufacturing Company Diffusely reflecting polarizing element including a first birefringent phase and a second phase
US5991077A (en) 1996-02-29 1999-11-23 3M Innovative Properties Company Multilayer polarizer having a continuous and disperse phase
US5783120A (en) 1996-02-29 1998-07-21 Minnesota Mining And Manufacturing Company Method for making an optical film
US6111696A (en) 1996-02-29 2000-08-29 3M Innovative Properties Company Brightness enhancement film
US6088159A (en) 1996-07-31 2000-07-11 Weber; Michael F. Reflective polarizers having extended red band edge for controlled off axis color
US5808794A (en) 1996-07-31 1998-09-15 Weber; Michael F. Reflective polarizers having extended red band edge for controlled off axis color
US5976424A (en) 1996-07-31 1999-11-02 Minnesota Mining And Manufacturing Company Method for making multilayer optical films having thin optical layers
EP0837351A2 (en) 1996-10-17 1998-04-22 Compaq Computer Corporation Projection display apparatus
US6390626B2 (en) * 1996-10-17 2002-05-21 Duke University Image projection system engine assembly
US6072629A (en) 1997-02-26 2000-06-06 Reveo, Inc. Polarizer devices and methods for making the same
US6721096B2 (en) 1997-10-28 2004-04-13 3M Innovative Properties Company Polarizing beam splitter
US6486997B1 (en) 1997-10-28 2002-11-26 3M Innovative Properties Company Reflective LCD projection system using wide-angle Cartesian polarizing beam splitter
US5999316A (en) 1997-12-06 1999-12-07 3M Innovative Properties Company Light valve with rotating polarizing element
US5940149A (en) 1997-12-11 1999-08-17 Minnesota Mining And Manufacturing Company Planar polarizer for LCD projectors
US6179948B1 (en) 1998-01-13 2001-01-30 3M Innovative Properties Company Optical film and process for manufacture thereof
US6157490A (en) 1998-01-13 2000-12-05 3M Innovative Properties Company Optical film with sharpened bandedge
US6667095B2 (en) 1998-01-13 2003-12-23 3M Innovative Properties Company Multicomponent optical body
US6157486A (en) 1998-01-13 2000-12-05 3M Innovative Properties Company Retroreflective dichroic reflector
US6207260B1 (en) 1998-01-13 2001-03-27 3M Innovative Properties Company Multicomponent optical body
US6024455A (en) 1998-01-13 2000-02-15 3M Innovative Properties Company Reflective article with concealed retroreflective pattern
US6012820A (en) 1998-01-13 2000-01-11 3M Innovative Properties Compnay Lighted hand-holdable novelty article
US6120026A (en) 1998-01-13 2000-09-19 3M Innovative Properties Co. Game with privacy material
US5999317A (en) 1998-01-13 1999-12-07 3M Innovative Properties Company Toy mirror with transmissive image mode
US6045894A (en) 1998-01-13 2000-04-04 3M Innovative Properties Company Clear to colored security film
US6111697A (en) 1998-01-13 2000-08-29 3M Innovative Properties Company Optical device with a dichroic polarizer and a multilayer optical film
US6352761B1 (en) 1998-01-13 2002-03-05 3M Innovative Properties Company Modified copolyesters and improved multilayer reflective films
US6113811A (en) 1998-01-13 2000-09-05 3M Innovative Properties Company Dichroic polarizing film and optical polarizer containing the film
US6053795A (en) 1998-01-13 2000-04-25 3M Innovative Properties Company Toy having image mode and changed image mode
US6049419A (en) 1998-01-13 2000-04-11 3M Innovative Properties Co Multilayer infrared reflecting optical body
US6082876A (en) 1998-01-13 2000-07-04 3M Innovative Properties Company Hand-holdable toy light tube with color changing film
US6531230B1 (en) 1998-01-13 2003-03-11 3M Innovative Properties Company Color shifting film
US6569515B2 (en) 1998-01-13 2003-05-27 3M Innovative Properties Company Multilayered polymer films with recyclable or recycled layers
US6096247A (en) 1998-07-31 2000-08-01 3M Innovative Properties Company Embossed optical polymer films
US6256146B1 (en) 1998-07-31 2001-07-03 3M Innovative Properties Post-forming continuous/disperse phase optical bodies
US6160663A (en) 1998-10-01 2000-12-12 3M Innovative Properties Company Film confined to a frame having relative anisotropic expansion characteristics
US6208466B1 (en) 1998-11-25 2001-03-27 3M Innovative Properties Company Multilayer reflector with selective transmission
US6322236B1 (en) 1999-02-09 2001-11-27 3M Innovative Properties Company Optical film with defect-reducing surface and method for making same
US6515785B1 (en) 1999-04-22 2003-02-04 3M Innovative Properties Company Optical devices using reflecting polarizing materials
US7023602B2 (en) 1999-05-17 2006-04-04 3M Innovative Properties Company Reflective LCD projection system using wide-angle Cartesian polarizing beam splitter and color separation and recombination prisms
US6672721B2 (en) * 2001-06-11 2004-01-06 3M Innovative Properties Company Projection system having low astigmatism
US6609795B2 (en) 2001-06-11 2003-08-26 3M Innovative Properties Company Polarizing beam splitter

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
3M Innovation, Vikuiti Dual Brightness Enhancement Film (DBEF), 3M IPC, Copyright @ 2000, 2001. *
A.E. Rosenbluth, D.B. Dove, F.E. Doany, R.N. Singh, Contrast properties of reflective liquid crystal light valves in projection displays, IBM J. Res. Develop vol. 42 No. 34 May-Jul. 1998 XP-000885154.
Schrenk et al., "Nanolayer polymeric optical films", Tappi Journal, pp. 169-174, Jun. 1992.
Weber et al., "Giant Birefringent Optics in Multilayer Polymer Mirrors," Science, vol. 287, No. 5462, pp. 2451-2456, Mar. 31, 2000.

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080285129A1 (en) * 2007-05-18 2008-11-20 3M Innovative Properties Company Color light combining system for optical projector
US7821713B2 (en) * 2007-05-18 2010-10-26 3M Innovative Properties Company Color light combining system for optical projector

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US20060098284A1 (en) 2006-05-11 application

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